Lightning strikes take out Google data

Google confirmed in a blog post some of its cloud computing services were affected last weekend following the storm (file)

It's often said lightning doesn't strike the same place twice, but four consecutive bolts that hit a power grid in Belgium briefly knocked some of Google's data centres offline.

Google confirmed in a blog post some of its cloud computing services were affected last weekend following the storm.

"The cabling alone can be struck anything up to a kilometre away, bring [the shock] back to the data centre and fuse everything that's in it," lightning protection service project manager Justin Gale told the BBC.

Google managed to restore most of the lost data, with only 0.000001 percent of its disk space in western Europe unable to be fixed.

"Although automatic auxiliary systems restored power quickly, and the storage systems are designed with battery backup, some recently written data was located on storage systems which were more susceptible to power failure from extended or repeated battery drain," the internet giant said in a statement.

"In almost all cases the data was successfully committed to stable storage, although manual intervention was required in order to restore the systems to their normal serving state. However, in a very few cases, recent writes were unrecoverable, leading to permanent data loss on the persistent disk."

Google has said it will upgrade the affected systems to try and prevent it happening again, but a spokesman for data centre consultants Future-Tech told the BBC it would be impossible to make them 100 percent secure.

"Everything in the data centre is connected one way or another," says James Wilman, Future-Tech engineering sales director.

"If you get four large strikes it wouldn't surprise me that it has affected the facility."

Google says while it accepts complete responsibility for the data loss, it recommends customers don't put all their data in one basket, and spread it around for this very reason.